As　a　heating　method　for　the　sustainability　of　residential　buildings　in　clean　space　heating,　carbon　dioxide　(CO2)　air　source　heat　pump　is　an　environment-friendly　solution　to　replace　fuel-fired　boiler.　Four　hybrid　configurations　of　vapor　injection　integrated　with　dedicated　mechanical　subcooling　(VI　+　DMS)　technologies　are　developed,　to　deal　with　the　problem　of　traditional　CO2　system　energy　efficiency　deterioration　in　cold　regions,　and　compared　with　traditional　transcritical　CO2　baseline　heat　pump　(BASE),　R410A　heat　pump,　coal-fired　boiler　and　four　CO2　heat　pump　systems　adopting　single　technique　of　VI　or　DMS.　Genetic　algorithm　is　utilized　to　optimize　the　operation　variables.　The　comprehensive　techno-energy-enviro-economics　performances　of　the　nine　systems　among　the　whole　lifetime　are　assessed.　The　influences　of　heating　terminal　selection　and　climate　condition　are　discussed　for　40　typical　cities　in　8　climate　zones　around　the　world.　The　results　demonstrate　a　maximum　coef-ficient　of　performance　(COP)　is　obtained　for　transcritical　CO2　vapor　injection　heat　pump　with　flash　tank　and　dedicated　mechanical　subcooling　(VI-FT-DMS),　and　the　COP　of　VI-FT-DMS　system　using　traditional　designed　radiator　as　heating　terminal　is　as　high　as　1.94　at　the　ambient　temperature　of-30　degrees　C.　The　hybrid　VI　+　DMS　CO2　heat　pump　achieves　a　significant　enhancement　in　heating　season　performance　factor　of　10.61　-30.37　%　and　the　throttling　irreversibility　can　be　remarkably　reduced　with　the　exergy　efficiency　promoted　by　12.76　-64.34　%.　The　life　cycle　cost　is　declined　by　14.71　-22.38　%　in　contrast　to　BASE,　and　life　cycle　carbon　emission　reduces　by　4.77　-22.12　%,　indicating　apparent　advantage　in　environmental　performance.　The　hybrid　VI　+　DMS　CO2　heat　pump　system　is　a　promising　solution　to　apply　for　clean　space　heating　in　the　cold,　very　cold　and　subarctic　zones.